A conventional inkjet printer includes a print-head assembly having an ink cartridge formed with a print-head at a bottom end thereof, and a stepper motor for moving the ink cartridge back and forth across a sheet of paper so that when the print-head runs over the paper, an image is formed on the paper. When the printer is not in use, the print-head assembly is parked at the maintenance region (on one side of the printer), where the print-head assembly is kept under the maintenance condition for conducting another printing operation upon receipt of a command.
A conventional print-head maintenance device generally includes a wiper for peeling the waste ink off the print-head and a shield for sealingly pressing against the periphery of the print-head so as to prevent vaporization of the ink in the nozzles, thereby avoiding untimely and undesired blockage of the nozzles in the print-head.
Referring to FIG. 1, a conventional print-head maintenance device 1 is shown to include a casing 10, a wiper unit 11 and a shielding unit 12. The casing 10 is shaped as a rectangle, and includes two side plates that cooperatively define a pair of straight guiding grooves 102 and a pair of inclined guiding grooves 101 behind the straight guiding grooves 102 and that define a receiving space therebetween for receiving the wiper unit 11 and the shielding unit 12 therein. The shielding unit 12 includes a sliding member 121 having front and rear pairs of engaging tongues received slidably in the straight and inclined guiding grooves 102, 101, an upper contact portion 1211 projecting upwardly from the sliding member 121, and a spring-loaded shield 122 mounted on the sliding member 121. A tension spring 13 interconnects the sliding member 121 and the casing 10 under tension. The wiper unit 11 is seated on the sliding member 121 behind the shielding unit 12 (see FIG. 2A), and has two pivots extending rotatably into two pivot holes in the casing 10 and a wiper 111 projecting perpendicularly from the sliding member 121.
Referring to FIG. 2A, upon finishing a printing operation, the ink cartridge C moves toward the maintenance region in the X direction (i.e. toward the left side of the printer), in which the print-head C1 make contact with the wiper t111, thereby removing the waste ink from the print-head C1.
Referring to FIG. 2B, as the ink cartridge C moves further (after the print-head C1 make contact with the wiper 111) for a distance of “D” in the X direction, collision of the cartridge C against the contact portion 1211 of the sliding member 121 results in vertical movement of the latter with respect to the casing 10, thereby raising the shielding 122 upward so as to press sealingly against the periphery of the print-head C1. Under this condition, the ink within the nozzles (not visible) of the print-head C1 is prevented from vaporization and blocking.
Note that the shield 122 contacts the print-head C1 in a sidewise manner since the sliding member 121 is raised gradually upward as it travels along the straight and inclined guiding grooves 102, 101 in the casing 10, thereby causing sidewise wearing of the shield 122. The sidewise wearing may decrease the hermetically sealing effect of the shield 122 with respect to the print-head C1, which, in turn, results in untimely drying of the ink in the print-head C1. It is noted that in the inkjet printer of nowadays, an air pump (not visible in the drawing) is generally installed in the print-head assembly in order to pump out the waste ink when the print-head assembly is parked at the maintenance region. Once the sidewise wearing is occurred, the pumping effect is accordingly reduced, i.e. the air pump is unable to pump out the waste ink effectively from the print-head.
Moreover, the casing 10 must reserve a distance of “D” (see FIG. 2B) in order to permit movement of the ink cartridge C into the maintenance region, during which the cartridge C make contact with the contact portion 1211 of the sliding member so as to result in movement of the latter in the casing 10. Under such arrangement, the maintenance region in the casing 10 is increased, which, in turn, causes increase in the overall length of the conventional inkjet printer. Since the manufacturers of the printers are in the trend to produce the printer in a compact design, a new design for the print-head maintenance device is badly in need to eliminate the drawbacks encountered during use of the conventional inkjet printer.